When a multi-row range is selected, this command creates multiple merged cells — one for eachrow.*Merge AcrossMerge CellUnmerge Cell

The command that creates multiple merged cells, one for each row, when a multi-row range is selected is "Merge Across".

Here are the steps to use this command in Excel:

1. Select the range of cells you want to merge. Make sure this is a multi-row range.
2. Go to the "Home" tab in the ribbon.
3. In the "Alignment" group, click on the "Merge & Center" drop-down arrow.
4. From the drop-down list, select "Merge Across".
5. Each row within the selected range will now be merged into one cell.

Please note that "Merge Cell" will merge all the selected cells into one single cell, and "Unmerge Cell" will unmerge any merged cells in the selection.